Neighbors dislike, and homeowner associations sometimes forbid, the ‘untidy’, ‘weedy’ native plants in our suburban gardens, when compared with the neatly mowed front yards that surround them, and there is no doubt that rolling swathes of green are extremely appealing. We justify this substitution by emphasizing that the right selection of native plants requires less irrigation (in most of California where rainfall needs to be supplemented, especially in summer) and also that they provide a natural habitat for the native fauna.

Now there is a further argument for replacing lawns; a UC Irvine study has pointed out that, although grass does absorb carbon dioxide and emits oxygen, as do all plants, the treatment that the typical lawn receives to keep it that smooth green carpet all year involves so much mowing, and often leaf blowing that the emissions from machinery, combined with nitrous oxide resulting from fertilizers, cancel out the carbon-saving benefits of the lawn.